Just go to any drug store, go to the cough and cold section and read the back of the bottle. DXM is an ingredient in the cough syrup, not the name of the cough medicine. You are making this really hard on yourself. We told you further up that DXM works and it's found in cough preparations and then you asked if we knew any cough syrups that potentiate your codeine. We don't know any by name since the members who answered you live in the US, but if it's in our cough meds then there's an extremely high likelihood that it's in yours.
How much of this DXM does one need to potenate codeine ? I have never used this DXM before. I have a cough syrup here that contains DXM 6.5mg per 5ml and also contains diphenhydramine.